Teeth sometimes weakly serrate in 15 or 16-1 or 2-15 or 16 large individuals; first tooth smaller than second, the 15th and 16th very small; teeth 1 through 3 in upper jaw nearly symmetrical and erect, with the subsequent teeth becoming increasingly oblique toward corners of mouth; cusps present on all teeth; lower teeth with somewhat narrower cusps than uppers, similarly oblique, but with successive series tending to become more erect and their cusps relatively more narrow with growth.